Low electrolyte level alarm devices

ABSTRACT

Two electrodes immersed in an electrolyte solution shunt the gate of a &#39;&#39;&#39;&#39;Triac&#39;&#39;&#39;&#39; solid state switching device connected in parallel with a current-limiting resistor which is connected via an alarm device across a power source. When the electrodes are immersed below the surface of the electrolyte, they serve as a closed switch drawing minimum current through the current limiting resistor, thus biasing the &#39;&#39;&#39;&#39;Triac&#39;&#39;&#39;&#39; in its nonconductive mode and trickling through the alarm device at amperage levels so low that the alarm device does not respond. When the electrolyte level falls, leaving the electrodes above the electrolyte solution, they become an open circuit. This reduces the trickle current to zero and applies full power source voltage to the gate of the &#39;&#39;&#39;&#39;Triac,&#39;&#39;&#39;&#39; triggering the &#39;&#39;&#39;&#39;Triac&#39;&#39;&#39;&#39; from a current blocking mode to a conductive mode. This permits an alarm current to pass through the &#39;&#39;&#39;&#39;Triac,&#39;&#39;&#39;&#39; thereby drawing this higher amperage current through the alarm device, producing an alarm signal indicating the level of the electrolyte.

United States Patent Sieron [451 Oct. 3, 1972 [72] Inventor: Richard L.Sieron, Old Saybrook,

Conn.

[73] Assignee: Dual-Lite Company, Newton, Conn.

[22] Filed: Sept. 14, 1970 211 Appl. No; 71,807

[52] US. Cl..... ..340/244 C, 307/252 [51] Int. Cl. ..G08b 21/00 [58]Field of Search .340/244, 244 C; 73/304, 304 C; 137/392 [56] ReferencesCited UNITED STATES PATENTS 3,498,131 3/1970 Rickey ..340/244 C3,131,335 4/1964 Berglund et a1 ..340/244 C 3,584,643 6/1971 Burke..340/244 3,257,643 6/ 1966 Jensen ..340/244 C 3,540,027 11/1970 Rauthet a1 ..340/244 C 3,373,351 3/1968 Rak ..73/304 Primary Examiner-ThomasB. Habecker Att0rney--Mattem, Ware & Davis [57] ABSTRACT Two electrodesimmersed in an electrolyte solution shunt the gate of a Triac solidstate switching device connected in parallel with a current-limitingresistor which is connected via an alarm device across a power source.When the electrodes are immersed below the surface of the electrolyte,they serve as a closed switch drawing minimum current through thecurrent limiting resistor, thus biasing the Triac in its non-conductivemode and trickling through the alarm device at amperage levels so lowthat the alarm device does not respond. When the electrolyte levelfalls, leaving the electrodes above the electrolyte solution, theybecome an open circuit. This reduces the trickle current to zero andapplies full power source voltage to the gate of the Triac, triggeringthe Triac from a current blocking mode to a conductive mode. Thispermits an alarm current to pass through the Triac, thereby drawing thishigher amperage current through the alarm device, producing an alarmsignal indicating the level of the electrolyte.

FLASHER PATENTED 067 3 I972 3, 6 96. 362

l 1 INVENTOR. RICHARD L. SIERON I MATTER/V WARE A/VD DAV/S ATTORNEYSterminal plating effect.

LOW ELECTROLYTE LEVEL ALARM DEVICES SUMMARY OF THE INVENTION Thisinvention relates to electrolyte level alarm devices, and moreparticularly to alarm devices for acid and alkaline liquid electrolytestorage batteries.

Existing electrolyte level indicating devices are undesirable since theyrequire operator initiation and surveillance. Furthermore, these systemsutilize the battery plates as part of their circuits, and generally arearranged to produce a positive indication when the electrolyte level isabove the fill point and to produce no indication when more electrolyteis required.

Therefore, it is a principal object of this invention to produce anelectrolyte level alarm device, capable of self-initiation of an alarmsignal when the electrolyte level is lower than desired.

Another object of this invention is to provide an electrolyte levelalarm device that is simple, reliable, and easily installed.

Another object of this invention is to provide an elec-.

trolyte level alarm device which not only indicates when electrolyte isneeded, but also reports a high charge condition caused by achargermalfunction before battery damage results.

A further object of this invention is to provide an electrolyte levelalarm device which operates independently of battery voltage, and avoidsdegradation of battery plates.

Another object is to provide an electrolyte level alarm device having anaudible alarm equipped with a fail-safe silencing switch, and a flashinglamp tell-tale reminder.

A further object is to provide an electrolyte level alarm device capableof disconnecting an associated battery charger upon actuation until thepredetermined electrolyte level is restored.

Another object of this invention is to provide an electrolyte levelalarm device capable of operating independently of the number ofexisting cells.

A still further object of this invention is to provide an electrolytelevel alarm device which requires no external electrical connection tothe normal battery chargedischarge terminals, and which is energized byan ex ternal alternating current source, avoiding any net Another objectof this invention is to provide a low electrolyte level alarm devicewhich operates independently and does not produce gas at eitherelectrode.

Another object of this invention is to provide a low electrolyte levelalarm device which incorporates a storage battery fill cap capable ofreplacing the conventional fill cap, so as not to require the drillingof a new hole in the battery casing.

Other and more specific objects will be apparent from the features,elements, combinations and operating procedures disclosed in thefollowing detailed description and shown in the drawings.

The low electrolyte level alarm device according to this inventionincorporates in a level sensor two electrodes which are immersed in theelectrolyte solution and perform as a switch which is closed when theelectrolyte is above the fill level and is open when the electrolytefalls below the fill level. The alarm device also incorporates atransformer which assures the proper voltage'level to the alarm circuit,a buzzer, a currentlimiting resistor, and a Triac solid state switchingdevice.

The transformer-buzzer alarm circuit includes the Triac in parallel withthe resistor, and the sensor electrodes shunt the Triacs gate. When theelectrodes are immersed in the electrolyte, the current flow path isthrough an alarm actuating relay coil, through the resistor, through theelectrolyte and back to the transformer. Since the resistor assures acurrent below l ma. the relay is not energized and the alarm does notoperate. When the electrolyte level falls below the electrodes, thesmall current through the resistor is interrupted, and full transformervoltage is applied to the Triacs gate, whereby the Triac is triggeredand acts as a virtual short by-passing the current-limiting resistor.This causes the amperage level in the circuit to increase greatly andinitiates operation of the buzzer and of a flashing lamp tell-talereminder.

The electrodes immersed in the electrolyte are sheathed with a thincoating of polymer material and are supported in a fill cap which may besubstituted for the standard fill cap of a storage battery. The polymercoating shields the electrode from the corrosive nature of theelectrolyte and the fillcap electrodes are connected with a socket plugfor easy removal from and connection to the alarm circuit. The lowelectrolyte level alarm device operates independently, without anyexternal electrical connection to the normal battery charge-dischargeterminals, and is simple, reliable and easily connected.

THE DRAWINGS FIG; 1 is a perspective view, partially in cross-section,of a level sensor having each two electrodes, sheathed with a thincoating of polymer material, and supported in a cap incorporating asocket plug connection; and

FIG. 2 is an electrical diagram of the associated circuit comprising thelow electrolyte alarm device.

DETAILED DESCRIPTION In FIG. 1, electrodes 21 and 22 are shown supportedin a fill cap 23. Electrode 21 comprises a conductive metal rod 24surrounded by a thin polymer coating 26, and electrode 22 comprises ametal rod 27 surrounded by a thin polymer coating 28. The terminatingend of electrode 21 is connected to a metal socket plug 37, and,similarly, electrode 22 is connected to a metal socket plug 38. Socketplugs 37 and 38 assure that electrodes 21 and 22 can be quicklydisconnected and connected to the alarm circuit ready for operation.

Electrode 21 and socket plug 37 are surroundingly supported withinplastic housing 31. Electrode 22 and socket plug 38 are similarly heldwithin plastic housing 32. Plastic housings 31 and 32 are adhesivelyanchored in holes 33 and 34 of cap 23. Also, cap 23 is provided with avent hole 39 to assure proper operation of the storage battery atatmospheric conditions.

The complete electrical diagram for the low electrolyte level alarmdevice is shown in FIG. 2. The input 1 l5-volt alternating current issupplied via lines 51 and 52 to transformer 53. Transformer 53 providesassurance that the alarm current on lines 54 and 62 through the alarmdevice circuit is isolated from the power line. Output line 54 from thesecondary winding nects junction 66 to the gate of Triac 59. Triac 59and electrode 22 are both connected by a line 62 to the secondarywinding of transformer 53.

When the level sensor electrodes 21 and 22 are immersed in electrolyte63, a monitoring current will be carried from electrode 21 throughelectrolyte 63 to electrode 22 and vice versa. Since the electrolytesresistance is extremely small in the immersed condition,

I the monitoring current path from transformer 53 will be along line 54through alarm relay 55, resistor 58, electrodes 21 and 22, and back totransformer 53 via line 62. Triac" 59 functions to block current flow,acting as an open circuit, and thereby assuring that only a low tricklemonitoring current flows through resistor 58 and electrodes 21 and 22 ata level insufficient to energize relay 55 to actuate buzzer 56.

Resistor 58 is preselected to assure that the monitoring currentthroughthe circuit will never exceed 1 ma. This low current precludesgas formation due to ionization at either. of the electrodes 21 and 22.Gas formation is also prevented by using alternating current, since thiscontinually changes the charge of electrodes 21 and 22.

At any time when the level of electrolyte 63 falls below electrodes 21and 22 to level 67, no monitoring current can pass between theelectrodes. When the trickle current through resistor 58 is therebyinterrupted, the full output potential of transformer 53 is appliedacross the gate of Triac 59 between lines 64 and 65, triggering thedevice to its conductive mode and shorting resistor 58. Since thecircuit now carries a high amperage level current, operation of alarmbuzzer 56 is initiated to warn that the electrolyte level has fallenbelow the desired point.

This high amperage current energizes relay 55, clos-, ing relay contacts55-1 to connect audible alarm 56 across the power linefContacts 55-1 areshown in their inactive mode in FIG. 2', energization of relay 55 raisesthe relay armature to close the upper contact 5-1, connecting alarm 56to the line in series with the upper armed contact 67 of a manualsilencer switch 68 whose lower disarmed contact 69 is connected to thoff contact 55-2 of relay 55.

Another relay contact 55-3 is connected via a fuse in series with theconventional fuse socket 70 of the battery charger. When relay 55 isenergized, contact 55-3 opens, serving as a circuit breaker,de-activating the charger until electrolyte is added to raise its levelto an operating depth.

A tell-tale flashing signal lamp 71 is connected in parallel with relay55, providing a visual alarm supplementing the audible alarm.

If electrolyte filling must be temporarily delayed, the audible alarm 56is silenced by moving the armature of manual silencing switch 68 fromits armed contact 67 to its disarmed? contact 69, but lamp 71 continuesflashing until electrolyte is restored.

When the fresh electrolyte 63 again permits monitoring current to flowbetween electrodes2l and 22, Triac 59 ceases to conduct, relay 55 isde-energized, relay contact 55-3 closes, again activating the batterycharger, and alarm contact 55-1 opens. If silencer switch 68 is in itsdisarmed mode, connecting contacts 69 and 55-2 to the power line, thisagain activates alarm 56' reminding the operator to switch the silencingswitch 68 to its armed contact 67, restoring the entire system to itsoperating mode, ready for alarm operation whenever electrolyte level 63again falls beyond the tips of electrodes 21 and 22.

In the preferred embodiment, the electrodes used depend upon thecomposition of the electrolyte. In an acid electrolyte such as thesulfuric acid solution used in the normal lead-acid battery, a tungstenelectrode is preferred since it has been discovered to be the metal mostcapable of resisting the corrosive nature of the acid. In an alkalineelectrolyte, such as potassium hydroxide, normally used in anickel-cadmium battery, the electrode materials found to be most capableof resisting. the corrosive nature of the alkaline solution are nickelplated steel or stainless steel.

The construction and arrangement of the electrodes is unique and solvesvarious problems existing in prior art systems. In the preferredconstruction of the electrodes, the electrodes will be full length andretained in a replacement fill cap. The full length of the electrodesallows them to be used in any application at any electrolyte leveldesired by simply cutting off the electrodes to meet the desired levelrequirements. Furthermore,

with potassium hydroxide electrolyte solutions, hydroxide creeps up theelectrodes by capillary action. If electrodes 21 and 22 are closetogether, this creeping coating may reach the underside of the cap 23and bridge the space between the electrodes, thereby carrying currenteven though the actual electrolyte level drops below. the electrodes.The electrodes according to this invention prevent potassium hydroxidecreep by remotely spacing the electrodes away from one another, nearopposite side edges of the cap 23, and by coating each of the electrodeswith an acid and alkaline resistant polymer sheath. This two foldapproach effectively prevents the potassium hydroxide from creeping upand bridging across the space between the electrodes. I I

Although a buzzer has been represented as the signalling device, anyattention-getting device could be used. Also, both the buzzer and theTriac in series can be connected in parallel with the resistor toaccomplish the desired signalling effect. The Triac em ployed in thepreferred embodiment is RCA type 4B527. The low electrolyte level alarmdevice of this invention is capable of effectively performing a dualfunction. The alarm device not only provides a positive signalindicating when the electrolyte requires the addition of water, but alsoprovides a positive signal indicating a high charge condition which maybe caused by any battery charger malfunction. The high charge conditioncauses the electrolyte to boil off, and when the electrolyte level fallsbelow the electrodes this condi tion will be efficiently reported by thealarm device which will summon the operator to the battery beforepermanent battery damage results. Also, the electrodes of this lowelectrolyte level alarm device are readily installed in any typicalstorage battery by merely replacing one of the fill caps with theelectrode fill cap combination. No additional hole need be drilled,since the electrode assembly replaces the conventional fill cap.

Since this low electrolyte level alarm device operates on 115 volt, 60Hz, alternating current, there are no polarity problems and no netplating effects resulting at the electrodes. The battery plates are notdegraded by the level alarm, and battery voltage is not drained tooperate the device. Furthermore, hydrogen product at either electrodein-sulfuric acid electrolyte solutionsis prevented by using alternatingsensing current and by employing a current-limiting resistor whichprevents the current through the electrolyte from exceeding 1 Aspreviously mentioned, the preferred electrodes employed depend upon thetype of electrolyte used, are

. substantially corrosion-proof, are easily adapted to any electrolytelevel desired, and eliminate any difficulty due to alkaline electrolytecreep.

Since the foregoing description and drawings are merely illustrative,the scope of the invention has been broadly stated herein and it shouldbe liberally interpreted so as to obtain the benefits of all equivalentsto which the invention is fairly entitled.

'What is claimed is:

l. A low electrolyte level alarm device comprising:

A. a source of alternating current electrical energy;

B. electrical warning alarm means for gaining attention of operatingpersonnel;

C. two electrodes normally conductively immersed in said electrolyte;and

D. automatic switching means connecting the warning means to the energysource, incorporating a thyristor device having a first main terminalconnected to said alternating current source and a second main terminalconnected through said alarm means to said source, and having a controlterminal connected through a current-limiting resistor to said secondmain terminal, with the two electrodes being directly connectedrespectively to said first main terminal and to said control terminal,

l. switchable from a non-conductive mode to a conductive mode inresponse to interruption of electrolyte conduction of resistor-limitedalternating monitoring current between the electrodes, I

2. thereby removing the electrolyte conduction shunt across the firstmain terminal and the control terminal, applying full triggeringpotential to the control terminal and completing a conductive circuitthrough the thyristor, the warning means and the energy source andinitiating a warning alarm operation of the warning means.

2. A low electrolyte level alarm device as defined in claim 1, whereinsaid warning means is a buzzer.

3. A low electrolyte level alarm device as defined in claim 1, whereinsaid electrolyte comprises an acid solution.

4. A low electrolyte level alarm device as defined in claim 3, whereinsaid electrodes each comprise an elongated tungsten conductive portionsurrounded by a thin layer of a nonconductive polymer material.

5. A low electrolyte level alarm device as defined in claim 1, whereinsaid electrolyte comprises an alkaline solution.

6. A low electrolyte level alarm device as defined in claim 5, whereinsaid electrodes each comprise an elongated stainless steel conductiveportion surrounded by a thin layer of a non-conductive polymer material.

7. A low electrolyte level alarm device as defined in claim 5, whereinsaid electrodes each comprise an elongated conductive nickel platedsteel portion surrounded by a thin layer of a non-conductive polymermaterial.

8. A low electrolyte level alarm device as defined in claim 1, whereinsaid thyristor device comprises a Triac, incorporating a gate controlterminal shunted to the first main terminal by the electrodes normallyconductively immersed in the electrolyte.

9. A low electrolyte level alarm device as defined in claim 1, whereinthe current drawn from said power source and limited by saidcurrent-limiting resistor does not exceed l ma. when said electrodes aretransferring monitoring current through said electrolyte.

10. The low electrolyte level alarm device defined in claim 1 whereinthe two electrodes are positioned in spaced-apart relation dependingfrom the underside of a storage battery fill cap for immersionside-by-side through the same battery fill port into the batteryelectrolyte.

11. The low electrolyte level alarm device defined in claim 1 whereinthe warning means includes an electromagnetic relay coil connected to beenergized by the energy source upon switching of the switching means toits conductive mode, with first normally open relay contacts interposedto connect a warning alarm device to a power source when said relay coilis energized to close said first contacts.

12. The device of claim 11 further including a visible warning deviceconnected in parallel with the relay coil to be actuated when the coilisenergized.

13. A low electrolyte level alarm device comprising:

A. a source of electrical energy;

E. electrical warning alarm means for gaining attention of operatingpersonnel;

C. two electrodes normally conductively immersed in said electrolyte;and i D. automatic switching means connecting the warning means to theenergy source 1. switchable from a non-conductive mode to a conductivemode in response to interruption of electrolyte conduction of monitoringcurrent between the electrodes, 2. thereby completing a conductivecircuit through the warning means and the energy source and initiatingwarning alarm operation of the warnmg means, wherein the warning meansincludes an electromagnetic relay coil connected to be energized by theenergy source upon switching of the energy source upon switching of theswitching means to its conductive mode, with first normally open relaycontacts interposed to connect a warning alarm device to a power sourcewhen said relay coil is energized to close said first contacts, andwherein a manual I double pole silencer switch is connected with a opensaidv closed pole and to disconnect the warn-' ing alarm device whilethe relay coil is energized, and with a normally open pole connected inseries with the normally closed first relay contacts, whereby the useris enabled to re-arm the device while the relay coil is de-energizedleaving only the normally open relay contacts as the sole break in thealarm device circuit. 14. A low electrolyte level alarm devicecomprising: A. a source of electrical energy; B. electrical warningalarm means for gaining attention of operating personnel; C. twoelectrodes normally conductively immersed in said electrolyte; and D.automatic switching means connecting the warning means to the energysource 1. switchable from a non-conductive mode to a conductive mode inresponse to interruption of electrolyte conduction of monitoring currentbetween the electrodes, 2. thereby completing a conductive circuitthrough the warning means and the energy source and initiating warningalarm operation of the Warning means,

wherein the warning means includes an electromagnetic relaycoilconnected to be energized by the energy source upon switching of theswitching means to its conductive mode, with first normally open relaycontacts interposed to connect a warning alarm device to a power sourcewhen said relay coil is energized to close said first contacts, furtherincluding a fuse and second normally closed relay contacts connected inseries with the fuse socket terminals of a battery charger which isoperatively connected to charge the battery whose electrolyte level isbeing sensed, automatically providing circuit breaker disconnection ofthe charger from its power supply when energization of the relay coilopens said second normally closed contacts.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent DatedOctober 3,

Inventor) Rlchard L, Sleron It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

Column 6, lines 61 & 62 "of the energy source upon -switching" should bedeleted from the text.

Signed and sealed this 20th day of February 1973.

(SEAL) Attest:

EDWARD}! FLE'I'CIIER IR ROBERT GOTTSCHALK Attostlng Officer Commissionerof Patents F ORM 0-1050 [10-69) USCOMM-DC 60376-P69 u.s. GOVERNMENYPRINTING OFFICE: I969 o-3es-334

1. A low electrolyte level alarm device comprising: A. a source ofalternating current electrical energy; B. electrical warning alarm meansfor gaining attention of operating personnel; C. two electrodes normallyconductively immersed in said electrolyte; and D. automatic switchingmeans connecting the warning means to the energy source, incorporating athyristor device having a first main terminal connected to saidalternating current source and a second main terminal connected throughsaid alarm means to said source, and having a control terminal connectedthrough a current-limiting resistor to said second main terminal, withthe two electrodes being directly connected respectively to said firstmain terminal and to said control terminal,
 1. switchable from anon-conductive mode to a conductive mode in response to interruption ofelectrolyte conduction of resistor-limited alternating monitoringcurrent between the electrodes,
 2. thereby removing the electrolyteconduction shunt across the first main terminal and the controlterminal, applying full triggering potential to the control terminal andcompleting a conductive circuit through the thyristor, the warning meansand the energy source and initiating warning alarm operation of thewarning means.
 2. thereby removing the electrolyte conduction shuntacross the first main terminal and the control terminal, applying fulltriggering potential to the control terminal and completing a conductivecircuit through the thyristor, the warning means and the energy sourceand initiating warning alarm operation of the warning means.
 2. A lowelectrolyte level alarm device as defined in claim 1, wherein saidwarning means is a buzzer.
 2. thereby completing a conductive circuitthrough the warning means and the energy source and initiating warningalarm operation of the warning means, wherein the warning means includesan electromagnetic relay coil connected to be energized by the energysource upon switching of the energy source upon switching of theswitching means to its conductive mode, with first normally open relaycontacts interposed to connect a warning alarm device to a power sourcewhen said relay coil is energized to close said first contacts, andwherein a manual double pole silencer switch is connected with anormally closed pole in series with the normally open first relaycontacts, permitting the user to open said closed pole and to disconnectthe warning alarm device while the relay coil is energized, and with anormally open pole connected in series with the normally closed firstrelay contacts, whereby the user is enabled to re-arm the device whilethe relay coil is de-energized leaving only the normally open relaycontacts as the sole break in the alarm device circuit.
 2. therebycompleting a conductive circuit through the warning means and the energysource and initiating warning alarm operation of the warning means,wherein the warning means includes an electromagnetic relay coilconnected to be energized by the energy source upon switching of theswitching means to its conductive mode, with first normally open relaycontacts interposed to connect a warning alarm device to a power sourcewhen said relay coil is energized to close said first contacts, furtherincluding a fuse and second normally closed relay contacts connected inseries with the fuse socket terminals of a battery charger which isoperatively connected to charge the battery whose electrolyte level isbeing sensed, automatically providing circuit breaker disconnection ofthe charger from its power supply when energization of the relay coilopens said second normally closed contacts.
 3. A low electrolyte levelalarm device as defined in claim 1, wherein said electrolyte comprisesan acid solution.
 4. A low electrolyte level alarm device as defined inclaim 3, wherein said electrodes each comprise an elongated tungstenconductive portion surrounded by a thin layer of a nonconductive polymermaterial.
 5. A low electrolyte level alarm device as defined in claim 1,wherein said electrolyte comprises an alkaline solution.
 6. A lowelectrolyte level alarm device as defined in claim 5, wherein saidelectrodes each comprise an elongated stainless steel conductive portionsurrounded by a thin layer of a non-conductive polymer material.
 7. Alow electrolyte level alarm device as defined in claim 5, wherein saidelectrodes each comprise an elongated conductive nickel plated steelportion surrounded by a thin layer of a non-conductive polymer material.8. A low electrolyte level alarm device as defined in claim 1, whereinsaid thyristor device comprises a ''''Triac,'''' incorporating a gatecontrol terminal shunted to the first main terminal by the electrodesnormally conductively immersed in the electrolyte.
 9. A low electrolytelevel alarm device as defined in claim 1, wherein the current drawn fromsaid power source and limited by said current-limiting resistor does notexceed 1 ma. when said electrodes are transferring monitoring currentthrough said electrolyte.
 10. The low electrolyte level alarm devicedefined in claim 1 wherein the two electrodes are positioned inspaced-apart relation depending from the underside of a storage batteryfill cap for immersion side-by-side through the same battery fill portinto the battery electrolyte.
 11. The low electrolyte level alarm devicedefined in claim 1 wherein the warning means includes an electromagneticrelay coil connected to be energized by the energy source upon switchingof the switching means to its conductive mode, with first normally openrelay contacts interposed to connect a warning alarm device to a powersource when said relay coil is energized to close said first contacts.12. The device of claim 11 further including a visible warning Deviceconnected in parallel with the relay coil to be actuated when the coilis energized.
 13. A low electrolyte level alarm device comprising: A. asource of electrical energy; B. electrical warning alarm means forgaining attention of operating personnel; C. two electrodes normallyconductively immersed in said electrolyte; and D. automatic switchingmeans connecting the warning means to the energy source
 14. A lowelectrolyte level alarm device comprising: A. a source of electricalenergy; B. electrical warning alarm means for gaining attention ofoperating personnel; C. two electrodes normally conductively immersed insaid electrolyte; and D. automatic switching means connecting thewarning means to the energy source